Overcurrent responsive relay control system for circuit breakers



July 25, l950 c. o. woon 2,516,167

ovERCuRRENT RESPONSIVE RELAY CONTROL SYSTEM FCR CIRCUIT BREAKERS Filed Jan. 22, 1945 2 sheets-sheet 1 @da 0 Ww@ @CMM 9 @ak `Filed Jan. 22, 1945 July 25, 1,950 c. o. woon 2,516,167

OVERCURRENT RESPONSIVE RELAY CONTROL SYSTEM FOR .CIRCUIT BREAKERS v 2 Sheets-Sheet 2 67/ l y f@ 67g 7i 6 677 665; Y Y @E f llo #NVE/vrom' fwf Wwi A rro RNE? Patented July 25, 1950 OVERCURRENT RESPONSIVE RELAY CON- TROL SYSTEM FOR CIRCUIT BREAKERS Claude 0. Wood, Chicago, Ill., assignor to Goodman Manufacturing Company, Chicago, Ill., a corporation of Illinois Application January 22, 1945, Serial No. 573,906

12 Claims. 1

l This invention relates to improvements in relays for controlling electric circuits.

The principal objects of my invention are to provide a novel form of statically balanced relay particularly adapted for use in mines, which will operate in any position it may happen to be in, without changing its calibration in any manner, and which will operate upon short circuit of the main line circuit and upon predetermined overload conditions of the main line circuit, and will positively be held in a position to hold the main line circuit open until the control circuit for said relay is manually broken.

In carrying out my invention I provide a statically balanced armature which is mounted for rocking movement intermediate its ends and biased to one position by means of a spring. I also provide two electromagnets which may be energized independently of each other, one of these magnets being on each side of the point of rocking movement of said armature for moving said armature against its bias. These electromagnets have independent electromagnetic structures and one is connected in series with the main line circuit to instantaneously operate said relay upon direct short circuit or momentary heavy overload of the main line circuit, While the other electromagnet is energized by means of a shunt coil, connected in a control line cir cuit, upon predetermined overload conditions in the main line circuit, or upon movement of the armature to a contra-biased position by the rst electromagnet, so said second electromagnet will serve to open the main line circuit upon predetermined overload conditions therein, and will positively hold said armature in a position to hold the main line circuit open until the circuit to said shunt coil is manually broken.

These and other objects of my invention will appear from time to time as the following speciiication proceeds and with reference to the accompanying drawings wherein:

Figure 1 is a view in side elevation of an overload relay constructed in accordance with my invention, with certain parts thereof broken away and certain other parts shown in substantially longitudinal section;

Figure 2 is a front elevation of the relay shown in Figure 1, with certain parts broken away and certain other parts shown in substantia1ly transverse section;

Figure 3 is an enlarged fragmentary detail isometric view showing certain details of the mounting for the armature of the relay;

' A'Figure 4 is an enlarged detail isometric View 2 showing certain details of the bimetal switch and the heater coil for causing said switch to close; and

Figures 5 and 6 are simplified diagrams of a motor control circuit employing an overload relay constructed in accordance with my invention, Figure 5 showing the relay in position to close the main line circuit, and Figure 6 showing the relay positioned to open the main line circuit.

Referring now to the drawings, the electromagnetic relay embodying my invention includes a base I0 made of suitable insulating material, such as impregnated and varnished hard wood, or slate, or a composition insulating material impervious to moisture, upon which is mounted a support member II forming a support for an armature I2, and for a series wound coil I4 of an electromagnet I5 and a shunt wound coil I6 of an electromagnetic switch I'I.

The series coil I4 has only a few turns and is placed in series with the connected load and is so designed and its magnetic circuit is such that normal operating and starting currents are not sufficient to cause it to operate the armature I2, but a ground in the motor, a short circuited rheostat, or momentary heavy overloads will cause sumcient current to flow through this coil so that it will operate the armature instantaneously.

The shunt coil I 6 is designed to attract the opposite end of the armature and operate the relay instantaneously when it is energized. This coil is energized when the relay is tripped by the series coil and serves to hold the relay open, until the circuit thereto is manually broken, and is also energized when the load on the main line circuit exceeds a predetermined value, as will hereinafter more clearly appear as this specification proceeds.

The support member II is of a substantially chair-shaped formation in side elevation and is formed from an angle bracket I8, secured at one of its legs to the base I0 and having a horizontal leg 20 extending outwardly from said base. Said horizontal leg has a leg 2| of an angle bracket 22 secured thereto and projecting outwardly therefrom. Said last mentioned angle bracket has an upright leg 23 which is connected to said base at its upper end by means of a tiebolt 24 encircled by a sleeve 25 of insulating material. Said last mentioned leg has a core 2'I of the electromagnet I 1 secured thereto and extending inwardly therefrom. A core 29 of the electromagnet I5 is secured to the vertical leg of the angle bracket I8, adjacent the lower end thereof.

and extends outwardly therefrom. Said support member and the cores of said electromagnets are preferably made from a suitable magnetic iron, such as low carbon iron known to the trade as Swedish or Arinco iron.

The armature I2 is likewise made from a suitable magnetic iron and is provided with two aligned transverse slots 30, 30 disposed intermediate its ends, which open to opposite sides thereof. Said slots are adapted to have prongs 3|, 3i of a bifurcated inner portionofthe leg 2.I of the bracket 22 extend therethrough and form a support for said armature. Said prongs extend along the upper side of and are secured to the leg 20 of the bracket I3 as by cap screws 33, 33 and the open slotted portion of said leg 2l, between said prongs, is spaced outwardly from the outer end of the leg 20 oi the bracket 22, a distance suiiicient to permit rocking movement of said armature on said support.

A spring 34 herein shown as being connected with the lower end of said armature is' provided to bias said armature into a position so that a contact member 35, extending upwardly from the upper end of said armature, may engage a contact member 36 mounted on the base Ill. When said contact members 35 and 3E are in engagement with each other, a control circuit will be closed, which will hold the main line circuit closed. When said armature is moved against its bias by means of either of the electromagnets l or I'I, the contact 35 will engage a contact 3i, which connects the shunt coil I6 in a control circuit and across the main line circuit, toV energize said shunt coil and cause the main line circuit to be heldk open by means of the electromagnet I7.

The spring 34, as herein shown, is connected to ay pin 39 mounted-in the lower end of said armature and extending outwardly therefrom. The opposite end of said spring is connected to a threaded adjusting screw 45, extending through an outer depending leg 4l' of a support member 52. A nut 43 is threaded on the end of said adjusting screw to adjust the tension of said spring.

The support member 52 has a depending inner leg M which is adapted to be engaged by the armature I2, to form a stop therefor and to determine its biased position.

The Contact 35 is mounted on the end of said armature opposite from the spring 34 on an insulating member 45, which is secured to the inner-face or said armature and projects upwardly therefrom. Said armature and the parts thereof including the contact 35 are balanced statically so that said armature will operate in any position in which it may be, without changing its calibration. This feature is especially desirable where the relay is to be used on electrical starting equipment in mines underground where space is limited, and where it isoften necessary to place the relay on its side or upside down from the position shown in the drawings, in order to conserve in space. It is also desirable where the relay is mounted in a separate starting box for operating conveyer or other equipment underground, in that the relay will operate if the starting box should accidentally be turned upside down or on its side.

A bimetal switch 39 is provided to connect the snunt wound coilv I5 in the main line circuit, to cause the electromagnet l1 to operate thev armature upon'predetermi'ned overload conditions in the main line circuit. Said bime'tal switch, as herein shown, includes a bimetallic element 50 having an inner end turned at right angles to the body portion thereof, which inner end is mounted on an insulating bracket member 5I by means of a nut and bolt 52 extending through said bracket member and through the base I0, and adapted to have an electrical conductor suitably connected thereto at the side of said base opposite from the armature i2. Said bimetallic element consists in a thin strip of bimetal which, due to its construction, distorts and bends when hea-ted. The outer end of said bimetallic element is adapted to engage a contact 53 when heated. Said Contact is mounted in the outer end of the bracket 5I and is adapted to have a suitable electric conductor connected thereto.

A heater coil 55 is mounted on the insulating bracket 5| and extends along and partially around the bimetallic element 5D, and forms a means for heating said element and causing it to deform and engage the contact 53, upon overload conditions in the main line circuit. Said heater coil, as herein shown, is connected in series with the connected load and with-the series coil I4 of the electromagnet I5, and is so constructed that normal operating loads will not cause it to heat sufficiently to deform the bimetallic element 55, to close its contacts, but that a predetermined maintained overload will cause this heater coil to heat suiciently to cause Said 1oimetallic element to bend and engage the con-- tact 53, to make a contact which will complete acircuit through the shunt coil of the relay, and cause the electromagnet Il to instantaneously operate the relay.

A conductor 5l, herein shown as being formed integrally with said series coil, extends downwardly therefrom and is secured to one end of said heater coil by means of a nut and bolt 59. The opposite end-of said heater coil is connected in the main line circuitby means of a suitable electric connector through a cap screw G0 threaded in a rectangular end 5I of a connecting bolt 62. Said connecting bolt extends through the base or the bracket 5t and the base I0 and is adapted to have a suitable electric conductor connected to its end, which is on the outside of said base.

Referring now in particular to Figures 5 and 6, showing the operating circuit for the overload relay of my invention, in Figure` 5 said relay is shown in a biased position. Inthis position the contact 35 engages the contact 36; When a push button switch 6l connected in a control circuit for starting a motor 515 is closed, `current will iow through said switch, control circuit contacts G'I-l of a main line contactor I, control circuit contacts 512 of a main line contactor 2, and through a coil 614 of a time delay relay 3 to ground. This will energize said coil to open contacts E'I'5 of. said relay and cut a resistance 515 into the circuit of the motor 510. Contacts 671 of said relay will also lclose to complete a circuit through a positive conductor 679, contacts 35 and 33 of the overload relay, and through a positive control circuit conductor 688i to and through the coils 55 and 65 of the contactors I and 2 to ground, to energize said coils and close main line and control circuit contacts 682 and 583 of contactor I and open control circuit contacts B'H of said contactor and will close main line contacts 635 oi contactor 2 and open control circuit contacts 572 of said contactor. This will connect the motor @le in the main line circuit through the series coil it and heater coil 55 of the overload relay. Opening .of the contacts `l'II and B12 will-disconnect the coil 614 of the time delay relay 3 from the control circuit, to permit said time delay relay to open in a predetermined delayed time interval and short circuit the resistance 616 out of the motor circuit. When said push button switch t1 is closed, and a ground occurs in the motor or a direct short circuit occurs in the rheostat or other parts of the circuit, the armature I2 Will be instantaneously moved against its bias by means of the electromagnet I5 energized by the series coil I4. This will disconnect the contact 35 from the contact 36 and will connect said contact 35 with the contact 3l. Engagement of the contact 35 with the contact 3'I will connect the shunt wound coil IB oi the electromagnet II in the control circuit, and cause said shunt coil and electromagnet to hold said armature against its bias. This will hold the circuit to the coils 65 and 56 open and thus will hold the main line contactors I and 2 open, and will prevent the passage oi current through the main line circuit until the control circuit through said shunt coil is broken, to permit the spring 3 i to move said armature to its biased position. 'Ihe circuit to said shunt coil is broke-n by pushing the push button switch Si' to its oii positicn, as shown in Figure 5.

When the push button 'I is in a closed cr on position and overload conditions are encountered, the heater coil 55 will heat the bimetallic element 56 of the bimetal switch i9 to the extent suiiicient to distort and bend said clement so it will engage the contact 53. This will connect thecontrol circuit through said bimetal switch and through the shunt wound coil I6 of the electromagnet I'I, to energize said magnet and move the armature I2 against its bias to open the circuit between the contacts 35 and 3S and close the circuit between the contacts 35 and 3T, and thus maintain the control circuit to the coils 65 and 65 in an open position until the relay is reset by pushing the push button G'I in a position to open the control circuit through said shunt coil through the contacts 35 and 31.

It may be seen from the foregoing that the control line circuit to the coils 55 and 66 is opened, to open the main line circuit, either upon direct short circuits or momentary heavy overload conditions in said main line circuit by means of the overload relay through the series coil I4 and electromagnet I5, and that said main line circuit is held in an open position by means oi the shunt coil IG and electromagnet il until said shunt coil is deenergized by opening the push button switch 57, at which time the spring 3d will move the armature i2 to its biased position to connect the contact 35 with the contact 36 and connect the operating coils of the contactors I and 2 in the control circuit.

It may further be seen that the bimetallic switch 49 operated by the heater coil 55 connects the shunt wound coil I8 in the control line circuit when predetermined overload conditions occur, to e-nergize said shunt coil and cause the electroniagnet I'I to attract and move the armature I2 against its bias, and disconnect the contact 35 from the contact 3B and connect the contact 35 with the contact 31, and hold said armature in a contra-biased position until the circuit to said coil is broken by operation of the push button B'I.

While I have herein shown and described one form in which my invention may be embodied, it will be understood that the construction thereof and the arrangement of the various parts may be alte-red without departing from the spirit and scope thereof. Furthermore, I do not Wish to be construed as limiting my invention to the specic embodiment illustrated, excepting as it may be limited in the appended claims.

I claim as my invention:

l. In an electromagnetic relay, an armature, an adjustable spring means for biasing said armature into a selected bias position, and two separately energized and independently operating electromagnets for moving said armature against its bias, one of said electromagnets being provided with a series wound coil connected in series with a main line electric circuit and adapted to operate said armature upon a short circuit in said main line circuit, and the other of said electromagnets being provided with a shunt wound coil adapted to be shunted across the main line circuit to operate said armature upon a predetermined overload of the main line circuit and also adapted to hold said armature in a contra-biased position irrespective of which of said electromagnets operates said armature, and means for energizing said shunt wound coil upon a predetermined overload in the main line circuit including a bimetal switch connected in series with said shunt coil, and a heater coil connected in series with said main line circuit, for operating said bimetal switch.

2. In an electromagnetic relay, an armature, a spring for biasing said armature into one position, and two separately energized electromagnets for moving said armature against its bias, one of said electromagnets being provided with a series wound coil connected in series with a main line electric circuit and adapted to operate said armature upon a short circuit in said circuit, and the other oi said electromagnets being provided with a shunt wound coil adapted to be shunted across the main line circuit to operate said armature upon a predetermined overload of the main line circuit, an electrical contact connected with said armature and adapted to close a circuit to energize said shunt coil upon operation or said armature by said series coil, to cause said shunt wound coil to hold said armature in a contra-biased position, and means for energizing said shunt Wound coil upon a predetermined overload in the main line circuit including a bimetal switch connected in series with said shunt coil, and a heater coil connected in series with said main line circuit for operating said bimetal switch.

3. In an electromagnetic relay, an armature mounted intermediate its ends for rocking movement, a spring for biasing said armature into one position, and two separately energized electromagnets for moving said armature against its bias, one of said electromagnets being on one side of the point of rocking movement of said armature and being directly connected in a. main line circuit, to operate said armature upon short circuit in the main line circuit, and the other of said electromagnets being on the opposite side of the point of rocking movement of said armature, a contact connected with said armature to shunt the coil of said other electromagnet across the main line circuit upon operation of said armature by said iirst electromagnet, to energize said coil of said other electromagnet and cause said electromagnet to hold said armature in a closed position, and other means for shunting said coil of said other electromagnet across the main line circuit upon a predetermined overload of said main line circuit.

4; In an electromagnetic relay, an armature mounted` for rocking movement intermediate its ends, a spring `for biasing said armature into one. position, and tvvok separately energized electromagnets for moving said armature against its bias, one of said electromagnets being on one side otthepoint of rocking movement of said armature and'` having a, series coil connected in series in a main line circuit, to` operate said armature upon. short: circuit in the main line circuit, and the other of. said electromagnets being on the opposite side of the point of rocking movement of said armature andv having a shunt coil adapted to be shunted. across the main line circuit, a contact connected with said armature, to energize said. shunt coil upon operation of said armature by Said first electromagnet, to cause said second electromagnet to hold' said armature in a closed position, and other means for energizing said shunt coil, to cause said second electromagnet to move said armature to a contra-biased position upon a, predetermined overload of said main line circuit'.

5. In an electromagnetic relay, an armature mountedintermediate its ends for rocking movement, a springv for biasing said armature into one position, and two separately energized electromagnets for moving said armature against its bias, one of said electromagnets being on one side of the point of rocking movement of said armature and havingr a Series coil connected in series in a main line circuit, to operate said arm mature upon lshort circuit in the main line circuit, and the other of said electromagnets being on the opposite side of the point of rocking movement of said armature and having a shunt coil adapted to be shunted across the main line circuit, a contact connected with said armature to energize said shunt coil upon operation of said armature by said rst electromagnet, to cause saidsecond electromagnet to hold said armature in a closed position, and other means for energizing said shuntv c oil, vto cause said second electromagnet to move said armature to a contrabiased position upon overload of said main line circuit, including a heater coil connected in series with said main line circuit and a bimetal switch closed by heating of said heater coil to a predetermined temperature, for connecting said second electromagnet in said circuit.

6. In an electromagnetic relay, a support meniber, an armature rockingly mounted intermediate its ends on said support member and balanced statically and soJ mounted on said support member'. as to operate in any position of said. relay, a spring for biasing said armature into one position, tvvov electromagnets disposed on opposite sides of the point of rocking movement of said armature, for moving said armature against its bias, to operate said relay, one of said electromagnets having a series coil connected in series with a main line circuit,l tooperate Said armature upon short. circuit in the main line circuit, and the other of said electromaenets having a shunt Wound coil, means: for energizing Said shunt coil, tov cause. said coil to move said larmature to a contra-biased position upon a predetermined overload .ou the main line circuit and to hold it in such a position including a switch operable upon a puede.termi-ned overloadY of the main line circuit ,forr energizing said Shunt Wound coil, and an electric Contact connected with Said armature, to close a circuit to said shunt coil upon movement oi` said armature to a contra-biased position, to cause saidshunt coll to hold said arma- 8 ture in. such a position until the circuitv to said shunt coil isbroken.

7; In. an electromagnetic relay, a support member, an armature rockingly mounted-intermedie ate its ends onsaidrsupportmember and balanced statically and. sov mounted onsaid support member as to operate in any position of said relay, a spring for biasing said armature into. OrlepQSition, twoseparately energized eleotromagnetsdisposed on opposite Sides ot the point of; rocking move;- ment of said armature, for moving said armatoro against its bias, to operate said relay, one of, said electromagnetshavine a .series woonden.- eratirle Coil connected in seriesvvith a main line circuit, to operato said armature upon short circuit in the mainline circuit,A and. theA other. of. said eleotromasnets having a shunt wouldv operating coll, and means for energizing said shunt coil., to cause-saidlcoll to move said armature to a contrabiased position to hold, it in. such ov position including. an electric contact connected with Said runat-ure to close e, circuit to said .shuntcol upon mov. nent of sa. .armati e to a contra-biased positionto. hol .seid arm ure such a position until the circuit to said shunt coll is broken, a bimetallic switch for connecting-said shunt Wound coil to the main line circuit upon apredetermined overload of said. circuit,L and a heater coil connected in seriesl with said main line circuit for cau-sing said loi-metallic ,switchl to operate.

8. In an electromagnetic protective device for controlling e Supply circuit to an electrically operated device, armature adapted to,` pivot at a teint intermediate its ends, e pair of electro- .megnets mounted .one on either side of the point of rocking movement of .said` armature and on opoosltesides thereof, Seid ermaturebeine. adapted upon energization of either of saidl electromaenets to move to a position to open the supply circuit to said electrically operated device., one o f sai-d electroniagnets being connected in series with said electrically operated device and adapted to move said armature to onen said `olrolzlit to said electrically operated device upon momentary overload in said .electrically operated. devloe, the other of ,said eleotromasnets being connected in shunt. with said electrically operated device and adapted to move said armature to, .open said oircuit to said electrically operated device upon a predetermined and prolonged overload thereof, said shunt. connected electromagnet also beine edaoted to .be energized upon movement of said armature by said series connectedl eleotromesnet to hold said circuit in open condition.

9. an elec romae-netlo protective device for controlling a supply circuit to an. electrically operated: device, all armature adopted to pvot at a point intermediate its ends, a ner of electromagnets mounted one on either Side Of lie point of reciting movement of said armature and on oponsite sides thereof, said armature beine adapted upon energization of `either of said electromagnets to move to a position to open the supply .oircut to said electrically onere-ted device one of said electroniaenets beine connected Series ith said electrically operated device and adaptl iature to onen Said circuit to i cally operated; deviceupon momentary in said electrically operated device, the other of said electromagnets; 'beine Connected in shunt with said electrically operated device and adapted to move ,se-id armature to onen seid eirc to. sad elec lily operated l vice upon a predetermined and prolonged .o .ood of said electrically operated devica. said s. connected electromagnet also being adapted to be energized, upon movement of said armature to an open cil-- cuit position, to hold said circuit in open condition irrespective of the condition of said series connected electromagnet in said circuit, and a thermally responsive switch for actuating said shunt connected electromagnet to move said armature to open said supply circuit upon predetermined overload of said electrically operated device.

10. In an electromagnetic protective device for controlling a supply circuit to an electrically operated device, an armature adapted to pivot at a point intermediate its ends, a pair of electromagnets mounted one on either side of the point of rocking movement of said armature and on opposite sides thereof, said armature being adapted upon energization of either oi said electromag nets to move to a position to open the supply circuit to said electrically operated device, one of said electromagnets being connected in series with said electrically operated device and adapted to move said armature to open said circuit to said electrically operated device upon momentary overload in said electrically operated device, the other of said electromagnets being connected in shunt With said electrically operated deVice and adapted to move said armature to open said cir= cuit to said electrically operated device upon a predetermined and prolonged overload of said electrically operated device, said shunt connected electromagnet also being adapted to be energized, upon movement of said armature to an open circuit position by either said series or shunt con nected electromagnet, to hold said circuit in open condition irrespective of the condition of said series connected electromagnet in said circuit.

11. In a circuit for controlling the supply of energy to an electrically operated device, a circuit for protecting against overload of said electrically operated device including a relay winding connected in series with said electrically operated device, a second relay winding connected in shunt with said electrically operated device, an armature cooperating with both of said relay windings adapted to control the supply of energy to said electrically operated device, said armature being movable upon a momentary overload in the series connected Winding to open the circuit through said electrically operated device, and a circuit closed upon movement of said armature for energizing said second relay winding and for maintaining the circuit through the electrically operated device in open condition, said second relay winding also being adapted to be energized upon a predetermined and prolonged overload of said electrically operated device to move said armature to open the circuit through said electrically operated device.

12. In a circuit for controlling the supply of energy to an electrically operated device, a circuit for protecting against overload of said electrically operated device including a relay winding connected in series with said electrically operated device, a second relay winding connected in shunt with said electrically operated device, an armature cooperating with both of said relay windings adapted to control the supply of energy to said electrically operated device, said armature being movable upon a momentary overload in the series connected winding to open the circuit through said electrically operated device, and a circuit closed upon movement of said armature for energizing said second relay winding and for maintaining the circuit through the electrically operated device in open condition, said second relay winding also being adapted to be energized upon a predetermined and prolonged overload of said electrically operated device to move said armature to open the circuit through said electrically operated device independently of and irrespective of the condition of said series winding in said circuit.

CLAUDE O. WOOD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 656,324 Holmes Aug. 21, 1900 1,314,530 Mardis Sept, 2, 1919 1,381,580 Moores et al June 14, 1921 1,644,525 Hoyler Oct. 4, 1927 1,705,676 Parsons Mar. 19, 1929 1,753,180 Whittingham Apr. 1, 1930 

